File: format.el.html

This file defines a unified mechanism for saving & loading files stored in different formats. format-alist contains information that directs Emacs to call an encoding or decoding function when reading or writing files that match certain conditions.

When a file is visited, its format is determined by matching the beginning of the file against regular expressions stored in format-alist. If this fails, you can manually translate the buffer using format-decode-buffer. In either case, the formats used are listed in the variable buffer-file-format, and become the default format for saving the buffer. To save a buffer in a different format, change this variable, or use format-write-file.

Auto-save files are normally created in the same format as the visited file, but the variable buffer-auto-save-file-format can be set to a particularly fast or otherwise preferred format to be used for auto-saving (or nil to do no encoding on auto-save files, but then you risk losing any text-properties in the buffer).

You can manually translate a buffer into or out of a particular format with the functions format-encode-buffer and format-decode-buffer. To translate just the region use the functions format-encode-region and format-decode-region.

You can define a new format by writing the encoding and decoding functions, and adding an entry to format-alist. See enriched.el for an example of how to implement a file format. There are various functions defined in this file that may be useful for writing the encoding and decoding functions:
 * format-annotate-region and format-deannotate-region allow a
    single alist of information to be used for encoding and decoding.
    The alist defines a correspondence between strings in the file ("annotations") and text-properties in the buffer. * format-replace-strings is similarly useful for doing simple string->string translations in a reversible manner.

Defined variables (1)

Defined functions (26)

Defined faces (0)